A problem with garbage disposals of the type that are commonly utilized in home and commercial kitchens is that the drain stopper gets stuck in the sink drain opening. When existing drain stoppers are inverted as a result of inadvertence or otherwise. This problem commonly occurs when the sink is utilized to wash dishes and is filled with water. When the washing is done, the drain stopper is unplugged and may be dropped back into the sink. It seems that more often than not, the drain stopper flips upside down, plugs the drain, and traps the water in the sink. Because the drain plug is inverted, it is difficult to pull the stopper out of the drain. There is no handle or grip on the bottom of a garbage disposal drain stopper. Most of the time, the drain stopper must be pried out by inserting a kitchen knife or screwdriver or other implement along the periphery of the stopper and prying. 
An additional problem with garbage disposal drains is that it is not uncommon for odors to emanate from the disposal. 